While Valve has still yet to produce an official installable image of SteamOS 3 for desktops, as always the community provides and another worth looking into is winesapOS. Another I covered is HoloISO, which tries to stick quite closely to SteamOS 3 but winesapOS aims to be a bit more than that.
Originally called the "Mac Linux Gaming Stick", the aim was to give macOS users an easy bootable disk to run Linux to get expanded game compatibility but it rebranded a while ago to expand the scope for many more users.
From what one of the developers told me:
Our ultimate goal is not to provide the exact SteamOS experience that the Steam Deck provides like HoloISO does. We are focused on the desktop experience and expanding support for SteamOS by making the operating system work on a wide range of hardware.
In keeping with that goal, they have expanded hardware support on desktops / laptops and of course Apple Mac systems too. They also have much more up to date software compared with SteamOS, it supports UEFI and legacy BIOS, encrypted filesystem support, has the Pamac application for installing / updating other software and comes pre-installed with plenty of software like Steam, Heroic Games Launcher, Lutris, and PolyMC while still keeping the look and feel similar to SteamOS 3.
A big new release with version 3.1.0 went up recently with these highlights:
- Arch Linux packages upgrades
- Graphics driver upgrades with support for Intel, NVIDIA and virtual machines
- Improved controller support
- An improved upgrade procedure
- A fork for the PlayStation 4
You can check out winesapOS on GitHub.